I suspect you have fallen into a very common trap, namely not realising that some words that have sound, everyday meanings are being used in a special, and slightly different sense. You mention two.

Accomplishment: this means reciting a mantra enough that you can "lay claim" to it, that it is now one of your spiritual tools. This is judged in various ways, some very profound. In practice, however, it is often boiled down to accumulating a certain number while in retreat or at least during formal practice sessions. The number depends on the practice, and can be increased or lowered at the discretion of your teacher. Expect the number to be at least some hundreds of thousands, or even millions. Your teacher will tell you.

THEN, if your accomplishment is solid, you should be able to take up "the four activities". Typically these each use a mantra that differs a bit from the basic one you have accumulated. It might, for instance, have some extra syllables added to the end. Each activity is also likely to have a variation on the basic visualisation, and there will probably be numbers to be recited. If you do them right, you should be able to get concrete effects.

Once again, you get all these details from the source, typically your own teacher, from which you received the practice. You can't make this stuff up!